1. Field of the Invention
The present invention relates to a digital multimedia broadcasting (DMB) service, and more particularly to system and method for providing the DMB confinement service.
2. Description of the Related Art
DMB service involves multiplexing digital broadcasting data corresponding to a plurality of programs compressed by a high-efficiency compression algorithm, for example, moving picture expert group (MPEG), then broadcasting through a satellite or terrestrial relay center via digital broadcast waves. Thus, it enables users to receive the data through a portable receiver or vehicle receiver. The digital broadcasting data is separated into video and audio data etc. to be compressed, divided into the transport packets (TP) of a designated unit, and multiplexed into a transport stream (TS) to be transmitted. The digital broadcasting data is multiplexed in each TS, so that a user can select and watch a desired program.
With the DMB service, the satellite DMB service became a charged service. Unlike the general TV broadcasting that emits the broadcasting to a majority, the satellite DMB service emits the broadcasting programs only to authorized subscribers and contains a conditional access system (CAS) for blocking unauthorized users.
FIG. 1 shows a configuration of the conventional digital multimedia broadcasting receiver, which includes an antenna 10, a DMB receiving module 20, a decoder module 30, a display unit 50, and a speaker 60. A confinement receiver 33, which confines the broadcasting reception, is employed in the decoder module 30. The construction of the digital multimedia broadcasting receiver shown in FIG. 1 may be applied to a mobile terminal.
In operation, the digital broadcasting signal received through the antenna 10 is reproduced into the original TS in the demodulator 21 of the DMB receiving module 20, the reproduced TS is corrected by the forward error correction (FEC) unit 23, and then input to the decoder module 30. A TS demultiplexer 31 demultiplexes the TS in which digital broadcasting data of a plurality of programs is multiplexed. The decoder module 30 extracts the TP that includes the digital broadcasting data of programs selected by users. Then, the digital broadcasting data is scrambled, that is, encrypted to be transmitted for the purpose of confinement reception. The CAS 33 of the decoder module 30, for example, descrambles, that is, decodes the encrypted digital broadcasting data using the scrambling key generated from a smart card 40. The decrypted digital broadcasting data is decoded in both an MPEG video decoder 35 and an MPEG audio decoder 37 of decoder module 30 to be supplied to users through both the display unit 50 and speaker 60.
Transport streams (TSs) have been considered only when program specific information (PSI) has an accurate packet identification description (PID) value of an audio/video elementary stream (ES) and demultiplexed with the audio/video ES. Since the PSI has an accurate PID value of audio/video ES, it is unsuitable to provide a free and/or charged multimedia service according to channels at the same time. Accordingly, the additional devices for authentication and copy guard, such as the CAS 33, are required. As a result, the configuration of the conventional DMB receiver is complicated, and additional cost is increased.